Conduit



heb; 3, 1931. LLLLLLL ZA 1,791,271

L. F. HARZA Feb. 3,*1931.

CONDUIT 5 Sheets-Sheet 2 Filed April 14 1924 v @il ,f77/ver? Feb. 3,1931. L, F HARZ 1,791,271

GONDUIT Filed April 14, 1924 5 Sheets-Sheet 5 i Patented Feb. 3, 1.931

' PATENT jor-'Fica 1 LEROY F.- HARZA', 0F cIIICAeo7 VILLINOIS ,i

` i Application meer Api-i1 14, 1924. seriai No. 706,234.`

This invention pertains generally to conduits employed for conductingwater or the like and more particularly to elbow conduits employed forchanging the direction'of How,

5 and while the principles of my invention may be embodied in -conduitsfor various purposes, the invention as illustrated herein is embodied ina draft tube of a hydraulic turbine.

ln hydraulic turbine installations the water must by necessity ofconstruction be deflectedr from the direct-ion in which it is dischargedfrom the turbine and inorder that the high velocity of the water at thedischarge of the turbine may bezgradually reduced to a low velocity withconsequent con-` version of the velocity'head discharged from theturbine into 'a pressure head at the discharge end of said.V conduit,the conduit or draft tube, in accordance with my invention,

is made of 'gradually increasing cross sectional area sothat it willcreate an increased suction head on the discharge side of the turbinewhich tends to increase the-effective head under which theturbineoperates and` thus lincreases the efliciencyof the turbine.

' If an elbow be employed in a draft tubek or other conduit of'uniformcircular or lother cross section, the water flowing therethrough becomesgreatly agitated and vdisturbed byl 2:0 its change of direction, andconsequently loses ra large amount of energy. turn at the elbow thewater tends to crowd against the outer circumference of the elbow bywhich .it is gradually deflected, but .thev

: water fails to follow thel inner circumference eddies and crosscurrents andwithout loss i through a conduit constructed in accordanceA15` of energy. v f f VWith this end 1n view, a condult constructed inaccordance with myinvention includes i an elbow, the outer circumferenceof which is gradually curved so as to deiect'the outer side of thestream, and the inner circumfer- In making the ence, instead of beingformed on an arc parallel with the arc of the outer circumference,isshaped to conform to the contourof the inner Vside of a free jet ofwater impinging tangentially.against the outer curved wall of the elbow;The-water therefore follows the inner wall Lof the elbow smoothly andrwithout the formation ofobjectionabl cross currentsl and eddies. Y

A free et of water impinging tangentially against av curved deflectivesurface either transversely flat or concave tends to'expand laterallyand to flatten voutinto a relatively thin, broad sheet of fan-like form.A theoretically perfect conduit `would be constructed to conformexactly-to the sha-pe of such a deflected and flattened stream;constructional limitations, however, practically preclude vthe buildingof a yconduit ofthe width to which` the stream ofwater would naturallyexpand during its travel to the point of ultimate discharge into thetail-water ofthe power plant.

Another object-of my present invention therefore is to provide a conduitwhich will accommodate this lateralv expansion of the.

stream but without exceeding the width within which it is advisable toconstruct a conduit. This desirable result is accomplished in myinvention by constructing the conduit so that it will gradually fold thelateral ,margins of the stream inwardly toward the center, therebyfbringing the overall lateral Vdimension,of the conduit withinreasonable limitations and without obstructing or disturbing thenatural.`

flow of the stream.V

Other objects and many of the inherent advantages of my inventionshouldbe readily appreciated as thelsame becomes better under-` tionwhen considered vin connect-ion with the y accompanying drawings.

Referring to the drawings: f i Fig. l 1s a diametric vertical sectionalview with my invention; Y

Fig 2 is aside elevation ishowinglithe ing tangentially against naturaliow ofa free/jet olf.,liquird imping-V Fig. 3 is a front elevation ofWhat is shown in Fig. 2;

Fig. l is a sectional View on the line l-t of Fig. 1;

.F ig. 5 is a similar view on the line 5 5 of Fig. 1;

F ig. 6 is a similar View on the line 6-6 of Fig. l;

Figs. 7 to 12,-inclusive, are one-half sectional views taken on thelines 7, 8, 9, 10, 11 and 12, respectively, of Fig. 1 showing theprogressive changes in the cross sec-tional contour of the conduit;

Fig. 13 is a full sectional View on the line 153-13 of Fig. 1;

Fig 11i is a similar vieuv showing a modified form of conduit;

Fig. 15 is a plan view showing the shape of the stream of Water as itpasses the elbow Fig. 16 is a view similar to Fig. et showing a conduithaving a convex instead of av flat outer deflecting Wall;

Fig. 17 is a view similar to Fig. 15 illustrating a modified form ofconduit;

Fig. 18 is a sectional View on the line 18-18 of Fig. 17;

Fig. 19 is a sectional view substantiall similar to Fig. 13 of a conduithaving a transversely curved instead of a flat bottom Wall; and

Figs. 20, 21 and 22 are sectional views of modified forms of conduitsembodying my invention.

yReferring now tothe drawings more in detail and first to Fig.. 2 and 3,reference ,y character 21 indicates a tube from which a jet of Water,indicated generally by 22, issues tangentially to a curved deflectingsurface 23. As Will be apparent from the drawings, the outer edge orsurface of the jet begins to diverge laterally from the point 2l Whereit first engages the deect-ing surface. d the natural divergence of sucha stream is shown in Fig. 3 Where reference character .ind etes thediverging lateral edges of the stream. The front edge of the stream.'that is, the one most remote from 'the deflecting surface 23, continuesdownwardly in a straight line until it encounters the deflectedfilaments of Water substantially at the point Q6 whereupon the filamentsof water of this portion of the stream are also deflected and thestream, When its direction has been completely changed, is of a broad,flat thin sheet of fan-lilre character of approximately the thicknessindicated by reference character 27. Figs. 2 and 3 therefore illustratethe shape that a circular stream of Water impinging tangentially againsta curved deflect-ing surface Will assume, and since this change of formof the stream is accomplished Vithout the establishment of eddies,swirls. or cross currents, it follows that a conduit shaped inconformity'With such a stream will conduct the Water in the most efiicient manner.

's i`lustrated n my in- :t

vention and constructed to connu( st*I of `water in substantially itsnormal comin explained in connection with Fig: rEhe conduit of Fig. 1 isshown as the drri't tube from turbine 28, andthe conduit is here shownto comprise first a vertical conical portion 29 gradually increasiug'insectional area for the purpose of convertingv the velocity head of thewater into a pressure head as is Well understood. Said conical portionleading from the turbine to section All (Fig. 1) is not a part of myinvention it is old in the art and not e seutial to the purpose of myinvention, which concerns only the elbouv und subsequent portion of thetube. The conical ferm of tube. as from the turbine to section All, isgenerally believed to be the most etlicient form of draft tube and assuch it is intended to use for such initial portion of the tube theeconomically available head room or vertical spaclimita-tions willpermit, thereafter applying my invention for eiiiciently deflecting theWater at right angles thereto. lf required to do so by economy oravailable vertical space,.the turbine would be mounted at section AA.Fig. l, the elbow comprising my inven-tion thus beginning immediately atthe turbine discharge.

The elbow by which the direction of stream of Water is changed comprisesa curved outer deflecting Wall B1k which extends from the outer end ofthe line ifi-A to the outer end of the line 12-12. T his surface asshown is cylindrical or curved in only one .direction Will be apparentfrom Figs. to l2, inclusive. although the effect will be sub. tautiallythe same if this curved surface also curved transversely as indicated byreferenre character 32 in Fig. 1G. this figure being a sectionsubstantially like the Jion shown in Fig. lV eXcept -tl at the de'l'lec0j Wall is transversely curved instead of he nu' flat in section. Thecross sef'ctiinal shape of the conduit on 'the line ilk-fi of F 1 iscircula r indicated by the dot ed lines in 'l, but as soon as thecurvature ol the der surface 31 begins, the side Walls o'frth duit arelaterally extended afliacent to the deilecting surface 31, providiiugpockets te accommodate the beginning of the lateral pension of thestream into a thin sheet uh is the Vfinal form.

As the surface ll progresses these poche-.s are gradually widened outinto the thin sheet and the originally cir i. o ition of the crosssectior bounded h surface 539,'Fig. 6, is correspondingly reduced untilit disappears altogether shown in Figs. and 3, l Y

lf the conduit were to con form crac/tlT7 to the shape of the streamillustrated in l lgs. i). and 3, the pockets il?) would continue tointlc-n ard 3.

time

f crease in lateral depth until the conduit would become iinpracticallywide. l have found,

'lioweve-I, that theconduitniaybbe confined within reasonable widthlimitations without obstructing or disturbing the flow of the stream tothe extentol' producing ob3ecti'on- .able eddies or cross currents, bygradually folding the margins of the 4streainjback toward the center-.These margins may be Jfoldedv either upwardly or downwardly, but

in the construction sliowii.i.iiFigs. 4 to 13,

inclusive, for illustrative purposes,the pockets of the conduit areturned upwardly and inwardly. Viewing `Figs 4 to 12 progressively itwill be apparent that the pockets 33 are extended laterally slightly inFig 4, then farther in Fig. 5. and. when the cross section G-l ot Fig. 1has been reached, the endsI of' the pockets are beginning to turnupwardly as indicated at 34 in Fig. 6y This up-' ward bending continuedat 7, from which it will also be observed that the ends 35 of thepockets begin to widen out to accomodate a greater volume of water.r In

8 9. 10 11 and 12 the'inward folding` 7 7 5 2*? of the pockets and theincrease in crosssectional area is progressively illustrated so thatwhen the cross section 12-12 olf-Fig. 1 is reached, the cross sectionalshape of the conduit will be like what is illustrated in Fig. l2, thisfigure, however, showing only one-halfr oiE the conduit. marginalportions of the conduit is continued until as the delivery ond of theconduit is approached it will appear in cross sectionsubstantially asshown in Fig. 13.l

fis explained in connection with Figs. 2

and 3, the filaments o'l' water striking the delieeting surface of theelbow tend to diverge laterally to produce a flat', thin fan-likestream. dicated by the lines ,36, 37 and 38m Fig. 15.

from which iig-'will be observed that they divergent filaments flowingintovthe lateral pockets of thecondiiit are deflected or folded overupon tlicn'iselves sotliat these filaments travel in a somewhat spiraliliath, the deflection being accomplished without disturbance l of thefilame and without the production essentially equivalentcross 'sectionin the' of eddies or objectionable rioss curi-ents.'

lt will be observed by cir-perline t and as illustrated in Figs. 2r and3 it the deflected side of the jetwill be forced to conform to' theconcave shape of the defiecting surface,

whether this be cylindrical or curved in both directions. The gradualencroachment of the deflecting surface upon tl'iecylindricalcontinuation of the voriginal section and di-`A l rsubrection of theietyresults'in ay grat traction from the eircular'section :of 'the jet onthe side ofv the .circle'adjacent to the de'- flecting surface', andthek substitution of an form of two iin-like protrusions or thin sheetsof water extending outward 'from the re- This inward folding of thevThedirection of divergence is iii-f ustricted' or deflected side of theoriginal v cylindricaljet as encroached upon by the deilecting surface.In the meantime the free side 'of the cylindrical jet, or Asideopposite2 the deflecting surface, V'continues with little change inshapefexcept by subtraction' of the segment of increasing altitude andeXcept for `a filet' of reverse curvature joining it' to the spreadingsheet. yAs shown in Figs. .-2 and 3,. Y the originalcylindrical jet isthuseventually all deflected into a thin sheet ofwater.' Figs. 4 and 16illustrate the beginning ofthe dcfleetion, leaving the main cylindricalstream unchanged except by encroachment upon its section andsubstitution oli` equivalent Varea of fan-lileo'r thin sheet of water.r

Thus, while' the radius of `the defiecting surfaceis subject to thechoice of thedesigner. the profile of thel opposite sid-eor inside ofthe deflected jet isnearly unafected bythe -deflecting surfaceuntilfdeflection is complete, Y, except that the sheet is joined to thecylindrical jet bya filet curve of small radius instead oit by acute orobtuse'angle. This filetcurveis usually, if not always, of smallerradius that that of the deficcting surface, unless the latter is veryyshort, Lwhich latter is a elusive, that the inner wall-39 graduallyapproaches the outer wall 31 so that the conduit becomes at the Ypoint 12-12 of gradually decreasing depth but' offli-ncreasing width to conformtothe natural thin sheet-like .shape of. the' stream flowingtherethrough.

Although my invei'itioii may be used in :inv conduit elbow as in a` pipeline where change inl cross section and velocity are-not desired, yet:torpurposes of hydraulic turbine dra'lt tubes, where this inventionwill find its chiell application, the cross sectional area of theconduit is, however, gradually"increasedl so that the conduites a wholewill' serve to convert the velocity head into a pressure head to producea highly efficient draft tube. Y

lVhile in the form of the invention thus far illustrated and describedthe margins of the stream have been folded upwardly and inwardly, itishould vbe' manifest that .they may equally well be folded downwardlyand inwardly, and in Fig. 14 I have illustrated such a. l. constructionrwherein the lateral pockets 'or extensions of' the conduit instead ofbeing folded upwardly, as shownv in Fig. 13, are folded downwardly. Theeffect upon isc 3. Anelbow conduit, the cross sectionalv shape of whichmerges from a circular forni forwardly of the curved portion into a wideshallow portion` beyond the curved portion, the margins of said shallowportion being gradually rolled toward tlie-`ceiiti'al plane of saidshallow portiontoreduce the overall fidth of said flattened portion ofthe conduit without diminishing the cross sectional area of saidconduit.

fl. An elbow conduit for changing the direction of iiow of a liquid andrecovering the energy therein, having a gradually curved deflectingouter w'all,'an iniiei wall shaped to conform substantiallyto'thecontour of i a free jet impinging tangentially against ysaid outer wall,and side walls diverging it ni the area of initial deflection, the crosssection of the conduit merging from a circle Vl'orwaidly of thedeflectin'g wall into a shallow widened form beyond said deiiectingwall, the margins of said widened portion being gradually folded back todecrease the overall width of the conduit. v

5. A longitudinally curved elbow conduit,v

substantially circular at its intake end, merging from the initial pointof longitudinal curv vature into a ribbon-like cross section al shape,

the 'margins o'f the conduit being gradually -folded inwardly from thepoint of initial curvature to reduce the overall width of the conduit. tv v 4 Y G i longitudinally curved deflecting conduitv of elbow shapeniergi'ngfrom a circle frz) into a flat cross'sectional shape, andhaving tie margins thereof Agradually folded inwardly from the point ofinitial longitudinal curvature to thereby minimize the voverall width ofthe conduit without obstructing the unrestricted iiow of liquidtherethrough.

7. A draft Vtube formed to provide an elbow, the shorter radius'of whichis shaped lo conform substantially to theinner contour of a free `iet ofliquidy iinpinging tangentially against the outer radius of the elbow,said conduit being flattened beyond the elbow and the margins thereofbeing gradually folded inwardlyy from the point `ofinitial longitudinal'curvature of the conduit, said folded niarginsbeing larger in verticaldimensions than the unfolded central portion of the conduit. y Y

8f ln a fluid conveying conduit, a portion oi'' substantiallyL circularcross section and a communicating bend or elbow comprising u, 'l ...,t,A. i i comprising an outer vcurved ,wa-.ll -o ture.

and 'an ,iiiiil' .curved `wall designed '.to con-v form substantiallylto the surface contour of the liiid at tlief merging iof the saidstream into said .ti'lin of fluit. ',diiiiier wall'being connected witht-liefa'ffor aid co'nlinigngwall to 'form' a" lose/d duct andAforming'therevsiith a confiningl surface which substantially con`foi-nis tothe'na't'iira'l 'stream if fluid y'when .iin-

pinged upontlie outer curifed dedectingwall ofthleselect'ed curvature:.A

; '9. In .a fluid' conveying conduit,

. @150W selected rature Vandwhich*'is substantially Aflatin ci wfhich'risv initially Asubst'a'iit'ially circular 'in dross 'sect'ioiiand4whi'fih changes fintofcircula'i ys ef jine'n'tal forin otprogressivelyVdecreasing altitude, wherebyL the fluidlstreain of ini-` tially'circularfforin cro/ss section when'iin pi'i'iged 'upon :said outerwallisprogressively changed into a thin fan-like ,film -of fluid by.

and upon vs'aid wall luntil substantially the 'sect-ion, jjoinedfbyconfining Awall.

entire"fcrssy sectional areaofsaid stream Ihas merged into the film, themerger effecting th eA introduction of fillet* curves of vtransitionfrom the n'a'l orrresidualcircular segment'of the stream into 4thefilnily and the conlining 'wall being fforined at theaiea-"of inerger'tof ,cnforinE substantially `to rtliese fiillet' cui es', ywhereby theconfininfgwallasiafwhole 1` substantially"conforms V*tothe fnaturalvconf tour of aV free stream of fluid when r'impinged upon the outerwallof'fthe selected'curva- 10. A conduit constructed substantially inaccordance with claimt) and wherein. the ou't-V er curved wallprogressively increases in' width from the inlet'toward the dischargeends of the conduit. Y l t 11. conduit constructed substantially inaccordance with claim 9 -and wherein the outer curved wallprogressively, increases in width from inlet toward discharge endsv oftions of said confining wall are turned outwardly into parallel spacedrelationto the said outer wall and are jointed thereto tol form anenclosure of progressively increasing width to accommodate the Said ilmof. i

l2. ln a lluid conveying conduit, a bend or elbou7 comprising a guidingsurface of selected curvature to deflect the fluid stream :fromitsoriginal course and an opposed conlining,r surface laterally joiningsaid guiding surface to complete the enclosure oi the fluid stream andforni an enclosed conduit, said opiliosing suriace being shaped anddisposed relaluiif'ely to said guiding' surface to conform substantiallyto the natural free surface assumed by the n'ian body of said lluidstream when deflected by said guiding suril'ace in the absence ci theopposing surface but votherwise flowing unconfined Without otherinfluence than initial velocity and to coniine the fluid stream to itsnatural free patlnsaid conduit being so constructed that its borechanges progressively from original section into a Wide7 thin divergent'fan-like chann cl. v'

13. il` hydraulic turbine draft tube of clbcw l'orin comprising aguidingrsur'face to fletlect the stre-ani i'rcni .its original courseand an opposed confining surlace to complete lhe enclosure oi `thestream and 'torni a closed duct therefor7 said opposed surface being'sha )ed and dis nosed relativel to said O'uidl a Y D ing surface todepart progressively by increasing dimensions and resulting crosssections but substantially similar geometrical section formed from thenaturally free surface which would be assumed by the original fluidstream if deflected by said guiding suriace in the absence of theopposed surface but otherwise flowingunconlin'ed Without other influencethan initial velocity, said confining draft tube transforming the fluidstream pro# grcssively as deflected from original section into a thintan-like divergent sheet of pro-v gressively increasing thickness inexcess of natural thickness to retard velocity, said tubeV lerniinatingin a portion shaped and having side passages therethroughtoreconsolidate said broad lilm into a stream of relatively narrowerWidth.

, LEROY F. HARZA.

